A strut type suspension used for a front wheel of an automobile has structure in which a strut assembly comprising a piston rod and a hydraulic shock absorber is combined with a coil spring. When a steering is operated, the strut assembly is rotated together with the coil spring. Accordingly, to support a load applied to the strut type suspension while allowing smooth rotation of the strut assembly, usually a bearing is placed between an upper mount which is a mounting mechanism for mounting the strut assembly onto the automobile body, and an upper spring seat which is a spring seat for the upper end of the coil spring.
For example, the Patent Literature 1 discloses a slide bearing of synthetic resin as a bearing for a strut type suspension. This slide bearing comprises: an upper case of synthetic resin which is mounted on the side of an upper mount; a lower case of synthetic resin which is mounted on the side of an upper spring seat and is rotatably combined with the upper case; and a center plate of synthetic resin for smooth rotation between the upper case and the lower case. Here, a plurality of grooves functioning as lubricating grease reservoir are formed in a bearing surface of the center plate, and these grooves are filled with lubricating grease. Further, a dust seal is located in a ring-shaped space so as to close a gap which is formed between the upper case and the lower case and leads to the ring-shaped space.
According to the slide bearing of synthetic resin described in the Patent Literature 1: the gap which is formed by combining the upper case and the lower case and leads to the outside of the ring-shaped space is closed; intrusion of dust, muddy water, or the like into the ring-shaped space can be prevented even under severe conditions; and thus it is possible to prevent deterioration of sliding performance owing to intrusion of dust, muddy water, or the like onto the bearing surface of the center plate placed in the ring-shaped space.